by DaveL » 18 Jan 2018, 18:32
Andy that unit will have a coil that is connected across the output side of the switch. When you press the green button you manually close the contacts and the the coil holds then closed. The emergency stop button will be in series with the coil, when you press it the coil is disconnected and the contacts are opened. You need to check it the wires for the emergency stop button are still firmly connected. Do you have a continuity tester (ohm meter), you can check if the contacts in the emergency stop button are closed (short circuit) when the button is not pressed.
All of the tests are of course carried out with it unplugged from the mains.
I have an external stop button on my Wadkin table saw and one of the wires came loose, the effect was what you are seeing.
It could also be caused by dust in the emergency stop switch stopping the contacts closing.
Edited to correct the auto correct!
Regards,
Dave
My tool kit is almost complete, only a few more to get.